Graduate School of Agricultural Science, Kobe University, Kobe, Japan.
Biol Reprod. 2012 Nov 8;87(5):113. doi: 10.1095/biolreprod.112.103119. Print 2012 Nov.
Recent research has shown that nucleoli of oocytes at the germinal vesicle (GV) stage (GV nucleoli) are not necessary for oocyte maturation but are essential for early embryonic development. Nucleoli of 2-cell embryos (2-cell nucleoli) have morphology similar to that of nucleoli in oocytes at the GV stage. In this study, we examined the ability of 2-cell nucleoli to substitute for GV nucleoli in terms of supporting early embryonic development by nucleolus aspiration (enucleolation) and transfer into metaphase II (MII) oocytes or 2-cell embryos that were derived from enucleolated oocytes at the GV stage in the pig. When 2-cell embryos were centrifuged to move the lipid droplets to one side of the blastomere, multiple nucleoli in the nucleus fused into a single nucleolus. The nucleoli were then aspirated from the 2-cell embryos by micromanipulation. The injection of 2-cell nucleoli to GV enucleolated oocytes at the MII stage rescued the embryos from the early embryonic arrest, and the resulting oocytes developed to blastocysts. However, the injection of 2-cell and GV nucleoli to 2-cell embryos derived from GV enucleolated oocytes rarely restored the development to blastocysts. These results indicate that 2-cell nucleoli support early embryonic development as GV nucleoli and that the presence of nucleoli is essential for pig embryos before the 2-cell stage.
最近的研究表明，卵母细胞生发泡（GV）期的核仁（GV 核仁）对于卵母细胞成熟并非必需，但对于早期胚胎发育却是必不可少的。2-细胞胚胎的核仁（2-细胞核仁）具有与 GV 期卵母细胞核仁相似的形态。在这项研究中，我们通过核仁抽吸（去核）将 2-细胞胚胎的核仁转移到 GV 期去核的卵母细胞或 2-细胞胚胎中，以检查其替代 GV 核仁的能力，从而支持早期胚胎发育。当 2-细胞胚胎被离心以将脂质滴移动到胚胎细胞的一侧时，细胞核中的多个核仁融合成一个核仁。然后通过显微操作从 2-细胞胚胎中抽吸核仁。将 2-细胞核仁注射到 MII 期 GV 去核的卵母细胞中，可以使胚胎从早期胚胎阻滞中恢复，并且得到的卵母细胞发育成囊胚。然而，将 2-细胞核仁和 GV 核仁注射到源自 GV 去核的卵母细胞的 2-细胞胚胎中，很少能恢复到囊胚发育。这些结果表明，2-细胞核仁可以像 GV 核仁一样支持早期胚胎发育，并且核仁的存在对于 2-细胞阶段之前的猪胚胎是必不可少的。
